Since the advent of automated word processing machinery beginning with the earliest automatically controllable typewriters and continuing on through the more sophisticated memory type word processing devices presently available there has been an increasing demand to provide a continuous supply of documents on which information can be put. The documents and work involved includes the automatic processing of business forms such as bills, the typing of letters on letterhead stationery, the addressing of envelopes as well as other types of repetitive work. In recent years, the preferred method of making such documents or business forms readily and continuously available has been by attaching them to a continuous carrier sheet which will transport them through the word processing equipment and from which they are subsequently removed following such processing.
There are a number of problems that must be overcome to properly prepare this document and carrier sheet product. The primary problem is registration. It is, of course, essential for typewritten material to be properly placed on each successive business form, such as bills. Thus, with each successive indexing movement of the carrier sheet through a word processor the next form must not only appear at the correct place, but it must also be correctly oriented on the carrier sheet both vertically and horizontally. Accordingly, it is necessary to properly attach such business forms to these carrier sheet substrates at precise locations and with a particular orientation.
Thus, at least one key element in the process of attaching forms or documents to carrier sheeting is to properly register each successive form at a predetermined position in the feed system and to develop and maintain the correct orientation so the document can be correctly placed on the carrier sheet substrate. When this is done each form subsequently coming into the word processor will be correctly positioned to receive information in the right location.
It is well recognized in the paper forms industry that documents feeders, such as rotary vacuum feeders, operate at relatively fast rates. Heretofore, it has not been possible to operate machines which attach documents to continuous carrier sheets at speeds comparable to those at which these feeders operate and still maintain registry of the documents. In one of the best known gluing machines, documents are essentially individually handled by a mechanical system. Each document is picked off from the bottom of a stack by a plurality of suction elements. The suction elements move the leading edge downwardly to a position where a plurality of gripping fingers can grab the document. The fingers are mounted on an arm which when moved pulls individual documents from the stack and moves them to a position above the carrier sheet on which glue spots had been previously placed. Movement of this finger arm is in a stop and go manner since the arm stops adjacent the supply and also when positioned above the carrier sheet. Accordingly, this provides a very slow feed but such a rate was necessary to allow documents to be correctly registered.
In order to produce an output rate that was acceptable relative to machine cost, prior art machines often employed multiple feed streams or paths so that several carrier sheets were being supplied simultaneously with documents from separate sources. Such multiple path devices were not without problems, however, since each path was driven from a common drive so that like documents had to be used in each stream. Also, if a problem of any kind developed in one stream requiring feeding to be stopped, the other stream was also rendered inoperative.
Such machines operating with two feed lines operating at an output rate of about 3300 documents per hour per stream produced a total hourly output of about 6600 documents.
Thus, it is extremely important to be able to accomplish gluing procedures in a relatively short amount of time not to make most efficient use of machine time and labor but in order to properly utilize the operational capabilities of rotary vacuum feeders.
Another problem concerns the difficulty in feeding documents so that lead documents are overlapped by following documents with the following document beneath the lead document. By overlapping documents in this manner, the leading edge of each document can be correctly positioned, documents are more easily oriented and documents are able to be correctly placed on the carrier sheet so that the trailing portion of leading documents lies on top of the leading portion of following documents.